The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Internet Protocol (IP) multicast conserves bandwidth and reduces traffic by simultaneously delivering a single stream of information to potentially thousands of subscribers while reducing processing burden on the source and the receivers. Multicast packets are replicated in the network at the point where paths diverge by routers enabled with Protocol Independent Multicast (PIM) and other supporting multicast protocols, resulting in the most efficient delivery of data to multiple receivers.
For example, subscribers to a multicast group may express interest in receiving a video data stream from a particular source by sending an Internet Group Management Protocol (IGMP) host report to routers in a network to which the subscribers are connected. The routers are then responsible for delivering data for the video data stream from the source to the receivers. The routers use PIM to dynamically create a multicast distribution tree. The video data stream is delivered only to the network segments that are in the path between the source and the subscriber devices.
Point-to-Multipoint (P2MP) is a method of communication for efficient multicast data distribution from a source to a set of receivers. Multi-Protocol Label Switching (MPLS) enables P2MP communication based on P2MP Label Switch Path (LSP), which can be configured by an operator in the context of the MPLS Transport Profile (MPLS-TP) or signaled through network protocols like Resource Reservation Protocol—Traffic Engineering (RSVP-TE) in the context of IP/MPLS.
A P2MP LSP may support a transport service, such as a pseudowire. A pseudowire “is a mechanism that emulates the essential attributes of a telecommunications service (such as a T1 leased line or Frame Relay) over a packet-switched network,” as described in Request for Comments (RFC) 3985, pages 2-3, published by the Internet Engineering Task Force (IETF). Pseudowires may encapsulate service-specific bit streams, cells, or protocol data units (PDUs) arriving at an ingress port and carrying them across a mechanism for data transport, such as an MPLS LSP.
Pseudowires may be created statically or dynamically. MPLS-TP, which is a simplified version of MPLS for transport networks, may be used to define a static LSP over which static pseudowires may be enabled. The MPLS-TP standard extends MPLS to include support for traditional transport operational models. MPLS-TP uses existing quality of service (QoS) and other support mechanisms already defined within the MPLS standards. Further, MPLS-TP includes the benefits of fast path protection, path-based in-band Operations, Administration, and Maintenance (OAM) protection mechanisms found in traditional transport technologies. MPLS-TP does not include some of the features associated with MPLS, including Penultimate Hop Popping (PHP), LSP merging, and Equal Cost Multi Path (ECMP). MPLS-TP does not require MPLS control plane capabilities and enables the management plane to set up LSPs manually.
Generalized MPLS (GMPLS) and RSVP-TE P2MP signaling can be used to set up an P2MP LSP over which a pseudowire may be run. These signaling protocols support P2MP extensions and the instantiation of explicitly routed LSPs, with or without resource reservations and independent of conventional IP routing. An explicitly routed path can be administratively specified, or automatically computed by a suitable entity based on quality of service (QoS) and policy requirements, taking into consideration the prevailing network state. (See RFC 3209, RFC 3473 and RFC 4875.)